The Calgary Stampede has released the cause of death for the first horse that went down during the Chuckwagon races last night, the horse died of an aortic aneurysm near the kidney.  After the first horse went down, two others followed.  In all three horses died, one other horse was hurt.

It happened in the fourth heat, when driver Chad Harden's left lead horse suddenly went down, that caused the other horses to tangle and fall as well.

The right lead horse and two of the outrider horses received life threatening injuries and were put down.

The right lead horse helped Chad Harden win the Rangeland Derby in 2009, and Harden was visibly upset after the accident. “They’re just like humans, they’re our family,” he said. “It’s just devastating for our whole family.”

The entire interview with Chad Harden is available here.

In light of this recent incident, the Calgary Animal Rights Effort will be protesting what it calls “the cruel and unnecessary use of animals” at the Calgary Stampede.  It has organized a protest for Friday evening and Saturday afternoon..

The Stampede tightened safety rules for the Chucks after 2010 which was a particularly bad year for the races; six horses died during that year’s Stampede.

Since then, all horses must be inspected by veterinarians before every race.

Horses must also get more rest time after every four hours of racing.

And fines for safety violations were raised substantially from about $2,000 to around $12,500.